Background

SOAs were designed to improve the reporting of small area statistics and are built up from groups of output areas (OA). Statistics for lower layer super output areas (LSOA) and middle layer super output areas (MSOA) were originally released in 2004 for England and Wales. Scotland also released statistics for data zones (DZ), that were equivalent to LSOAs, in 2004 and intermediate geographies (IG), that were equivalent to MSOAs, in 2005. Northern Ireland introduced LSOAs in 2005 but do not have an MSOA geography.

2011 Super Output Areas

Maintaining stability as far as possible was key for the 2011 Census. LSOAs and MSOAs created following the 2001 Census continue to exist unless a significant population change occurred between 2001 and 2011, and household minimum and maximum thresholds were breached. Simplistically, where populations have become too big, the LSOAs/MSOAs have been split into two or more areas; where populations have become too small, the LSOAs/MSOAs have been merged with an adjacent one. Responses to the Output Geography Consultation from December 2009 to March 2010 were also considered in the redesign of OAs and SOAs. Consequently, the total changes across the OA hierarchy were no more than 5% overall.

Population and household minimum and maximum thresholds for SOAs in England and Wales:

Geography

Minimum population

Maximum population

Minimum number of houseolds

Maximum number of households

LSOA

1,000

3,000

400

1,200

MSOA

5,000

15,000

2,000

6,000

The total of 2011 LSOAs and MSOAs for England and Wales:

Geography

England

Wales

LSOA

32,844

1,909

MSOA

6,791

410

DZs and intermediate zones (IZ) in Scotland were reviewed following the 2011 Census and minor changes were implemented, similar to those in England and Wales.

SOAs in Northern Ireland have had minimal changes in three areas, but the total number of SOAs has not changed since the 2011 Census. Further details of Northern Ireland LSOAs can be found on the NISRA website.

Significant points of interest for the 2011 Census are that SOAs align to local authority district (LAD) boundaries including those that changed between 2003 and 2011, and also align at the border between Scotland and England.

Furthermore, the boundaries are available clipped to the coastline, for mapping, as well as to the extent of the realm, for geographic information systems and analysis. All SOAs have unique nine-character codes, in line with all statistical geographies we provide.

An upper layer super output area layer will not be created for England as part of the 2011 Census OA hierarchy.

2001 Super Output Areas

2001 SOAs were initially introduced for use on the Neighbourhood Statistics (NeSS) website, but later became the standard units for presenting local statistical information across National Statistics.

Local statistics were produced at electoral ward/division level before OAs and SOAs were introduced. This had drawbacks because electoral wards/divisions vary greatly in size, from fewer than 100 residents to more than 30,000.

This was not ideal for nationwide comparisons, and also meant that some data could not be released for smaller wards due to disclosure issues and the need to protect the confidentiality of individuals.

DZs and IGs in Scotland are smaller in population size than their LSOA and MSOA counterparts in England and Wales. DZs have a minimum population of 500 and IGs have a minimum population of 2,500.

In Northern Ireland, LSOAs have a population threshold of between 1,300 and 2,800.